Impact testing machine



Oct. 5, 1948. I u, HQFMANN 2,450,662

IMPACT TESTING MACHINE Filed Feb. 26, 1945 v 2 Sheets-Sheet 1 ATTORNEY Q 1948; RVU. HOFMANN IMPACT TESTING MACHINE 2 Sheets-Sheet 2 Filed Feb. 26, 1945 eil Patented Oct. 5, 1 948 IMPACT TESTING MACHINE Richard U. Hofmann, Rye, N. Y., assignor, by

mesne assignments, to The Baldwin Locomotive Works, a corporation of Pennsylvania Application February 26, 1945, Serial No. 579,804

' 4 Claims.

This invention relates to impact testing machines of the type employing a pendulum hammer and it is an object of my invention to provide improved means for releasing the pendulum and of braking the same after a specimen has been broken.

Another object is to provide an improved release and brake mechanism that is relatively simple in construction. operation and maintenance and which requires minimum thought and attention on the part of the operator.

In accomplishing the foregoing as well as other objects, such as will be apparent to those skilled in the art, I have specifically provided a single operating handle or lever having three positions, namely, latching, releasing and braking. With the lever in the latched position the pendulum. hammer when raised to its correct height is automatically latched and held. The hand lever is then moved to its releasing position and is finally moved to its braking position after the specimen is broken. This allows the operator to perform the releasing and braking operations with a single direction of movement and to have all three operations of latching, releasing and braking under the control of this one lever.

Other objects and advantage will be more apparent to those skilled in the art from the follow" ing description of the accompanying drawings in which:

Fig. 1 is a perspective of an impact testing machine embodying my improved control and showing the pendulum hammer in its raised position;

Fig. 2 is a transverse section taken in a vertical plane generally indicated by line 2-2 of Fig. 4, but for purposes of clarity certain parts are shown in elevation and the releasing pin is also included;

Fig. 3 is a horizontal section taken substantially on the line 33 of Fig. 2; and

Fig. 4 is an enlarged fragmentary perspective of my improved control mechanism partly broken away to show the relation of parts.

In the drawings I have shown for purposes of illustration an impact machine of a well-known type having a base i, a vertical standard 2 and a pendulum hammer 3 pivotally supported about an-axis 4. Suitable specimen holder 5 for Izod or Charpy specimens are mounted upon base i and the hammer 3 is adapted to fall from a predetermined height and impart an impact blow to the specimen. A usual indicating hand and dial 6 indicate the foot pounds of energy required to break the specimen.

My improved mechanism is used in cooperation with a drum 7 to which the pendulum 3 is attached and which has two locking shoulders or elements 8 and 9. To latch up the pendulum a bolt l 0 is vertically slidable in a brake shoe sleeve l l. A pin l2 extends through a slot l3 in the upper end of bolt l0 and thence outwardly through the brake sleeve I I. This pin terminates at its outer ends in vertical slots l4 formed in a cover l5 which is removably secured to a frame portion 16 formed as a part of and overhanging from the upper end of standard 2. The lower end of the brake sleeve H is provided with a brake shoe l1 adapted to engage the braking surface, preferably the periphery, of drum 1 while a spring I 8 interposed between a flange on the brake shoe and a stationary part of frame portion l6 normally biases the brake shoe to a. braking position. The brake shoe l'l together with its portion specifically shown in the form of sleeve II, are referred to herein as the brake shoe element. To disengage the brake by holding the brake shoe out of braking engagement with drum 1 a roller 20 is mounted on pin 12 and rides upon the surface 2| of a cam 2| that is journ-alled on and rotatable about the vertical axis of sleeve II. This cam surface has two depressions 22 and 23 preferably on diametrically opposite sides and connected together by fiat surfaces such as 2|. Certain of these cam surfaces also function to release the locking bolt 40 by the provision of a pin 25 secured to the bolt and extending outwardly therefrom through a vertical slot 26 in brake sleeve ll, Fig. 4. The cam surface 2| is shown in Fig. 4 as. holding the pin 25 in raised position to release the bolt I0. The bolt I0 is norm-ally biased downwardly toward the locking position by a spring 21.

In operation, a handle 29 secured to cam 2| and extending outwardly therefrom through a semicircular slot partially shown at 38, Fig. 4, is first moved slightly to the right from the position shown in Fig. 4 whereupon pin 25 drops into cam recess 23 thereby allowing locking bolt H) to move down under the force of spring l8 so as to be engaged by one or the other of latches 8 or 9 during counterclockwise movement of hammer 3 to its raised position. During thi time roller 20 is riding on the raised cam surface 2| so that pin l2 holds brake sleeve H in a raised position. To release pendulum hammer 3 hand lever 29 is moved to the position shown in Fig. 4 in which case pin 25 has been lifted by the inclined cam surface of recess 23 thereby to disengage the lower end of locking bolt H) from the latch elements 8 or 9. The pendulum then swings down and imparts an impact blow to the specimen held in holder 5 and after the pendulum has moved to its maximum height after fracturing the specimen the hand lever 29, Fig. 4, is then moved further to the left until roller 20 drops into cam recess 23, Figs. 2 and 3. Thereupon spring I8 forces brake shoe l1 into engagement with drum I to slow down the swinging action of the pendulum and quickly bring the pendulum to rest.

The hand lever 29 may be left in its locking position untilthe next test is started whereupon.

cam surfaces are of course maintained in a pre'- determined relation to each other by the body structure of element 2i on which the cam surfaces are formed. The cams, their followers and element 12, etc., for holding them in a predetermined relation constitute mechanism for effecting a predetermined sequence of operations of the'release and braking functions. The handle 29 constitutes means for operating such mechanism.

From the foregoing disclosure, it is seen that I have provided a combined pendulum release and brake mechanism that is relatively simple in construction, operation and maintenance combined with ruggedness and yet has ease and flexibility ofv operation. The cooperative relation of the various elements produces a very compact device which may be readily incorporated in the head of the machine frame. It will of course be understood that various changes in details of construction and arrangement of parts may be made by those skilled in the art without departing from the spirit of the invention as setforth in the appended claims.

Iclaim:

1. A combined pendulum release and brake mechanism for a pendulum impact testing machine of the type having a brake surface and a latching element comprising, in combination, a latch bolt element adapted to engage the latching element to hold the pendulum in a raised position and to be released to allow the pendulum to move through its impact stroke, a brake shoe element adapted to engage the brake surface to bring the pendulum to rest after a testing operation, mechanism for effecting a predetermined sequence of operation of said elements, means for operating said mechanism, said latch bolt and brake shoe elements being arranged substantially concentric to each other and extending away from said brake surface; and the sequence mechanism being disposed at the outer end of said concentrically arranged elements.

2. A combined pendulum release and brake mechanism for a pendulum impact testing machine of the type having albrake surface and a latching element comprising'in combination, a latch bolt element adapted to engage the latching element to hold the pendulum in a raised position and to be released to allow the pendulum to move through its impact stroke, a brake shoe element adapted to engage the brake surface to bring the pendulum to rest after a testmg operation, mechanism for efiectinga predeterminedsequence of operation of said elements, means ,for operating said mechanism, the brake shoe element having a sleeve through which the latch bolt extends, and the sequence'mecham'sm including a cam coaxial of said bolt and afollower connected to said bolt extending through said sleeve for engagement with said cam, and

another follower connected to said sleeve and adapted to engage said cam whereby relative movement between said followers andrc'am causes the desired sequence of operation of first releasing the latch bolt and subsequently allowing applicatlon of the brake.

3. A combined pendulum release and brake mechanism for a pendulum impact testing machine of the type having a brake surface and a latching element comprising, in combination, a

latch bolt element adapted to engage the latching element to hold the pendulum in a raised position and to be released to allow the pendulum to move through its impact stroke, a brake shoe element adapted to engage the brake surface to bring the pendulum to rest after a testing operation, mechanism for effecting a predetermined sequence of operation of said elements, means for operating said mechanism, the brake shoe element having a sleeve and the latch bolt extending therethrough, and the mechanism for effecting a predetermined sequence of operations includes a rotatable cam arranged coaxially of said sleeve, a follower for the latch bolt'extending therefrom through said sleeve for engagement with the cam surface, and a follower connected to the sleeve for engagement with the cam and the cam being rotated by the operating means to effect the desired sequence of operation of the latch and brake shoe.

4. A combined pendulum release and brake mechanism for a pendulum impact testing machine of the type having a brake surface and a latching element comprising, in combination, a latch bolt element adapted to engage the latching element to hold the pendulum in a raised position and to be released to allow the pendulum to move through its impact stroke, a'brake shoe element adapted to engage the brake surface to bring the pendulum to rest after a testing operation, mechanism for eifecting a predetermined sequence of operation of said elements, means for operating said mechanism, the brake shoe element having a sleeve and the latch bolt extending therethrough, and the mechanism=i0r effecting a predetermined sequence of operations includes a rotatable cam arranged coaxiallyof said sleeve, a follower for the latch-bolt extending therefrom through said sleeve for engagement with the cam surface, a follower connected to the sleeve for engagement with the cam and the cam being rotated by the operating means to eifect the desired sequence of operation of the latch and brake shoe, and springs for biasing the latch bolt in a latching direction and the brake shoe in a braking directiomand the-cam being arranged to hold said brake shoe and latching bolt in released positions against the biasing action of said springs until released by rotation of the cam.

RICHARD U. HOFMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 586,745 Pierce et a1. July 20, 1897 1,780,696 Amsler Nov. 4, 1930 2,139,527 Sonntag Dec. 6,.1938 2,359,044 MacBride Sept. 26; 1944 

